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A005355
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Number of asymmetric permutation rooted trees with n nodes.
(Formerly M2680)
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1
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0, 1, 1, 1, 3, 7, 21, 61, 187, 577, 1825, 5831, 18883, 61699, 203429, 675545, 2258291, 7592249, 25656477, 87096661, 296891287, 1015797379, 3487272317, 12008898531, 41471260883, 143588078449, 498343911529, 1733410858955
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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REFERENCES
| Labelle, Gilbert; Counting asymmetric enriched trees. J. Symbolic Comput. 14 (1992), no. 2-3, 211-242.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
| Index entries for sequences related to rooted trees
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FORMULA
| Shifts left under transform T where Ta has g.f. (1-A(x^2))/(1-A(x)).
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CROSSREFS
| Cf. A004111, A050383.
Sequence in context: A183113 A102877 A122983 * A025235 A129366 A166358
Adjacent sequences: A005352 A005353 A005354 * A005356 A005357 A005358
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KEYWORD
| nonn,nice,easy,eigen
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe, Susanna Cuyler
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EXTENSIONS
| More terms, formula from Christian G. Bower (bowerc(AT)usa.net), Nov 15 1999.
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